1. Field of the Invention
The present invention relates to an ice maker of refrigerators wherein water contained in an ice tray is refrigerated so that ice is made and a method of detecting water unsupplied condition of the ice tray when the water has not been supplied to the ice tray in spite of execution of the water supply operation.
2. Description of the Prior Art
An automatic ice maker incorporated in refrigerators conventionally comprises an ice tray disposed in a freezing compartment or exclusive ice making compartment, a reservoir tank disposed in a storage compartment and a water supply pump for supplying water in a reservoir tank to the ice tray.
In the above-described ice maker, water is first supplied to the ice tray by the water supply pump and the water in the ice tray is refrggerated so that ice is obtained. When the ice is made, the ice tray is reversed so that the ice is remove from the ice tray. The ice is received by an ice dispenser dispose beneath the ice tray. Thereafter, when the ice tray is again reversed to the former position, water is re-supplied to the ice tray by the water supply pump. The above-described operation is reiteratively executed and more and more lumps of ice are reserved in the ice dispenser.
Japanese Published Patent Application (Kokoku) No. 5111338 and Japanese Published Utility Model Application (Kokoku) No. 52-2928 disclose means for detecting the change of water in the ice tray into ice so that the ice tray is reversed. These publications disclose a method of detecting completion of an ice making operation cycle by sensing the temperature of the ice tray which is decreased below 0.degree. C. when the water in the ice tray is changed to ice. More specifically, a temperature sensor such as a thermistor is mounted on the ice tray and it is determined that the ice making operation cycle is completed when the temperature of the ice tray detected by the sensor takes a predetermined small value. Then, switch means comprising electronic circuitry is activated in response to temperature detection signal so that an electric drive motor is energized to reverse the ice tray. After tee ice tray is reversed and lumps of ice are removed therefrom, the ice tray is again reversed to the former position and the water is again supplied thereto. The water supply to the ice tray causes the temperature of the ice tray to be increased. The temperature increase of the ice tray is sensed by the temperature sensor and the motor is deenergized by the switch means when the temperature sensed by the temperature sensor takes a predetermined large value.
According to the conventional ice maker of the refrigerator, the ice making operation cycle from the water supply to the ice tray to the removal of ice therefrom can be reiterated by detecting the changing of water in the ice tray into ice. The water in the reservoir tank is decreased with reiterative execution of the ice making operation cycle. Conventionally, a user observes the residual quantity of water in the reservoir tank and water is added or supplied in case of need.
However, when the user forgets to supply water to the reservoir tank, the tank will be emptied. Consequently, water is not supplied to the ice tray even though the water supply pump is driven to supply water to the ice tray and accordingly, ice will not be made.
In the above-described condition, the user finds out that smaller number of lumps of ice has been reserved in the ice dispenser and that the reservoir tank has been emptied only when he or she takes out the lumps of ice from the ice dispenser. Consequently, a problem arises that a necessary amount of ice cannot be obtained when the user needs the ice.
In order to solve the above-described problem, the condition that water has not been supplied to the ice tray needs to be detected. However, such a detecting method or device has not been devised nor actualized as far as the inventors know.